HYDRAULIC HORIZONS MAKING WAVES WITH HYDRAULICS Wave-like microstructure used in hydraulic pumps to increase load carrying and efficiency
BY DAWN M. GESKE The mobile equipment industry has paid particular focus on the efficiency of equipment by increasing the performance of the engine and drivetrain to not only de- crease fuel consumption but provide overall operational efficiency. Work is currently being done on the efficiency of hydraulic pumps to increase their potential load-carrying capacity and reduce their energy losses. Working with the Center for Compact and Efficient Fluid Power (CCEFP), Dr. Monika Ivantysynova, director of the Maha Fluid Power Research Center at Purdue University in the School of Mechanical Engineering and Depart- ment of Agricultural and Biological Engineering, along with a group of graduate and undergraduate students and visiting researchers, has spent a great amount of time looking at the possibility of increasing load-carrying ability of pump-critical interfaces and pump efficiency by using wave-like surfaces versus flat surfaces. The Maha Fluid Power Research Center is a member of the CCEFP, with a working laboratory in Lafayette, Ind. The Maha Fluid Power Research Center’s first laboratory was formed in 2004 and moved from its original location to a new and larger building in Lafayette in the summer of 2008. The Lafayette facility was recently up- graded with a semi-anechoic acoustic
chamber to allow sound intensity measurements on hydraulic pumps, motors and transmissions. The study of wave-like microstruc- turing of surfaces of hydraulic compo- nents grew out of an initial thought that sliding surfaces within the cylin- der block and valve plate should be smooth. The research group initially thought that a smooth surface would produce the most efficient operation and help to prevent wear. The lubricating gap between the cylinder block and valve plate serves two functions necessary for proper machine operation. The gap serves to seal the individual dis- placement chambers and provides a combined hydrostatic-hydrodynamic axial sliding bearing to support the cylinder block. Previous simulation work using a coupled fluid-structure interaction model of the cylinder block-valve plate interface has shown that apply- ing a microstructured waved surface to one of the sliding surfaces of the cylinder block-valve plate significantly reduced the power loss at partial load conditions in this interface. An extensive simulation study per- formed by the Maha Fluid Power Research Center showed the effects of different wave amplitude, wave fre- quency, pump design and operational The Maha Fluid Power Research Center at Purdue University has researched the possi- bility of increasing load-carrying ability of pump-critical interfaces and pump efficiency by using wave-like surfaces versus flat sur- faces. The image on the right is an illustration of the fluid and structural mesh for the cylin- der block-valve plate gap.